Hard to tell looking at the picture, but such things happen now and then. It is a combination of several factors - water has to freeze on the surface and on the edges first in such a way, that the connection between ice and the vessel is wateproof. Then when water freezes it pushes itself outside through a final opening, freezing on the edges - and that creates a tube sticking out. You should be able to google images with a correct selection of keywords.

It happens quite often and has to do with the way the water freezes. I'm not sure whether I still get it right. The water freezes outside-in. Since it freezes simultaneously from the ground to the top and freezing water requires more volume than liquid, some water is pushed up in the center where it's still liquid and then freezing in the air.

darcidoo

the Weather channel program "Strangest Weather on Earth" did a spot on this very thing and explained it well, better than I could. Same thing happened last week in my ice cube tray in the freezer, does NOT happen every time, conditions have to be special. Check out the weather channel.

I believe water expands when cooled from 4C to 0C (in other words, heat DOES NOT rise)..
The way I could see this happening is that if it started to freeze and the water below was warm(ish) still, there'd be a point where the ice on the top leaves only a small hole of water, it freezes the edges of the hole, and meanwhile the rest of the water is still expanding since it's cooling from 4C to 0C, this expansion has to go somewhere, so it pushes water out of the small remaining hole, continually freezing around the edges, and forming an upside down icicle.

Water expanding when cooled from 4C to 0C and heat sinking at those temperatures has many implications, and one is the reason it's hard to melt snow in a pan, the heat sinks.. Another is that the bottom of a lake will stay warm enough for fish to survive the winter.